metrics: Make WebVitalMetrics Class Trivially Copyable

In order to use the WebVitalMetrics class with shared memory in the
follow up CLs, make the WebVitalMetrics class trivially copyable.

R=sadrul

Bug: 1151343
Change-Id: Ib613198bfc0b54667b4048ab9e2eefe16b4fbdf6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2602383Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: weiliangc <weiliangc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841635}

cc/layers/heads_up_display_layer_impl.cc

@@ -1097,10 +1097,11 @@ int HeadsUpDisplayLayerImpl::DrawSingleMetric(
     int top,
     std::string name,
     const WebVitalMetrics::MetricsInfo& info,
+    bool has_value,
     double value) const {
   std::string value_str = "-";
   SkColor metrics_color = DebugColors::HUDTitleColor();
-  if (value >= 0.f) {
+  if (has_value) {
     value_str = ToStringTwoDecimalPrecision(value) + info.UnitToString();
     if (value < info.green_threshold)
       metrics_color = SK_ColorGREEN;
@@ -1132,25 +1133,27 @@ SkRect HeadsUpDisplayLayerImpl::DrawWebVitalMetrics(PaintCanvas* canvas,
   DrawGraphBackground(canvas, &flags, area);
 
   int current_top = top + metrics_sizes.kTopPadding + metrics_sizes.kFontHeight;
-  double lcp_value = -1;
-  if (web_vital_metrics_ &&
-      web_vital_metrics_->largest_contentful_paint.has_value())
-    lcp_value = web_vital_metrics_->largest_contentful_paint->InSecondsF();
-  current_top = DrawSingleMetric(canvas, left, left + width, current_top,
-                                 "Largest Contentful Paint",
-                                 WebVitalMetrics::lcp_info, lcp_value);
+  double metric_value = 0.f;
+  bool has_lcp = web_vital_metrics_ && web_vital_metrics_->has_lcp;
+  if (has_lcp)
+    metric_value = web_vital_metrics_->largest_contentful_paint.InSecondsF();
+  current_top = DrawSingleMetric(
+      canvas, left, left + width, current_top, "Largest Contentful Paint",
+      WebVitalMetrics::lcp_info, has_lcp, metric_value);
 
-  double fid_value = -1;
-  if (web_vital_metrics_ && web_vital_metrics_->first_input_delay.has_value())
-    fid_value = web_vital_metrics_->first_input_delay->InMillisecondsF();
+  bool has_fid = web_vital_metrics_ && web_vital_metrics_->has_fid;
+  if (has_fid)
+    metric_value = web_vital_metrics_->first_input_delay.InMillisecondsF();
   current_top = DrawSingleMetric(canvas, left, left + width, current_top,
                                  "First Input Delay", WebVitalMetrics::fid_info,
-                                 fid_value);
+                                 has_fid, metric_value);
 
+  bool has_layout_shift = web_vital_metrics_ && web_vital_metrics_->has_cls;
+  if (has_layout_shift)
+    metric_value = web_vital_metrics_->layout_shift;
   current_top = DrawSingleMetric(
       canvas, left, left + width, current_top, "Cumulative Layout Shift",
-      WebVitalMetrics::cls_info,
-      web_vital_metrics_ ? web_vital_metrics_->layout_shift : -1);
+      WebVitalMetrics::cls_info, has_layout_shift, metric_value);
 
   return area;
 }

cc/layers/heads_up_display_layer_impl.h

@@ -143,6 +143,7 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
                        int top,
                        std::string name,
                        const WebVitalMetrics::MetricsInfo& info,
+                       bool has_value,
                        double value) const;
   SkRect DrawWebVitalMetrics(PaintCanvas* canvas,
                              int left,

cc/metrics/web_vital_metrics.cc

@@ -10,21 +10,4 @@ constexpr WebVitalMetrics::MetricsInfo WebVitalMetrics::lcp_info;
 constexpr WebVitalMetrics::MetricsInfo WebVitalMetrics::fid_info;
 constexpr WebVitalMetrics::MetricsInfo WebVitalMetrics::cls_info;
 
-WebVitalMetrics::WebVitalMetrics() = default;
-
-WebVitalMetrics::WebVitalMetrics(const WebVitalMetrics& other) = default;
-
-bool WebVitalMetrics::HasValue() const {
-  if (largest_contentful_paint.has_value())
-    return true;
-
-  if (first_input_delay.has_value())
-    return true;
-
-  if (layout_shift > 0.f)
-    return true;
-
-  return false;
-}
-
 }  // namespace cc

cc/metrics/web_vital_metrics.h

@@ -14,14 +14,17 @@ namespace cc {
 
 // Web Vital metrics reported from blink to be displayed with cc's HUD display.
 struct CC_EXPORT WebVitalMetrics {
-  base::Optional<base::TimeDelta> largest_contentful_paint;
-  base::Optional<base::TimeDelta> first_input_delay;
+  bool has_lcp = false;
+  base::TimeDelta largest_contentful_paint;
+  bool has_fid = false;
+  base::TimeDelta first_input_delay;
+  bool has_cls = false;
   double layout_shift = 0.f;
 
-  WebVitalMetrics();
-  WebVitalMetrics(const WebVitalMetrics& other);
+  WebVitalMetrics() = default;
+  WebVitalMetrics(const WebVitalMetrics& other) = default;
 
-  bool HasValue() const;
+  bool HasValue() const { return has_lcp || has_fid || has_cls; }
 
   struct MetricsInfo {
     double green_threshold;

third_party/blink/renderer/core/frame/web_frame_widget_impl.cc

@@ -2119,22 +2119,28 @@ std::unique_ptr<cc::WebVitalMetrics> WebFrameWidgetImpl::GetWebVitalMetrics() {
   // This class should be called at most once per commit.
   WebPerformance perf = LocalRootImpl()->Performance();
   auto metrics = std::make_unique<cc::WebVitalMetrics>();
-  if (perf.FirstInputDelay().has_value())
-    metrics->first_input_delay = *perf.FirstInputDelay();
+  if (perf.FirstInputDelay().has_value()) {
+    metrics->first_input_delay = perf.FirstInputDelay().value();
+    metrics->has_fid = true;
+  }
 
   base::TimeTicks start = perf.NavigationStartAsMonotonicTime();
   base::TimeTicks largest_contentful_paint =
       perf.LargestContentfulPaintAsMonotonicTime();
-  if (largest_contentful_paint >= start)
+  if (largest_contentful_paint >= start) {
     metrics->largest_contentful_paint = largest_contentful_paint - start;
+    metrics->has_lcp = true;
+  }
 
   double layout_shift = LocalRootImpl()
                             ->GetFrame()
                             ->View()
                             ->GetLayoutShiftTracker()
                             .WeightedScore();
-  if (layout_shift > 0.f)
+  if (layout_shift > 0.f) {
     metrics->layout_shift = layout_shift;
+    metrics->has_cls = true;
+  }
 
   if (!metrics->HasValue())
     return nullptr;